Overhead garage door systems are widely used in both residential and commercial applications, and are designed to be operated either manually or automatically through a reversible motor. Overhead garage doors include a series of interconnected door panels that are connected along their longitudinal edges by one or more hinges to provide pivotal movement of the door panels between vertical and horizontal positions as is known in the art. The door panels include a series of roller brackets mounted on opposite sides of the door panels for supporting a series of rollers. The rollers travel in a pair of continuous tracks mounted on opposite sides of a door frame for guiding movement of the door panels between the vertical and horizontal positions.
Overhead garage door systems include tracks in which the garage door travels. The tracks are typically mounted to a door frame through bracket and fastener assemblies. Each door track includes a horizontal track that extends generally parallel to the garage ceiling and has an integral radius section for guiding movement of the garage door between the horizontal and vertical positions. Each door track further includes a vertical track that is mounted generally parallel to the door frame or jamb which provides a linear extension of the radius section which extends from the horizontal track. Depending on the size of the garage door opening and the available overhead room, different horizontal track radiuses are used to accommodate for different installation requirements. That is, one installation may require a ten inch radius section connected to the horizontal track while another installation may require a twelve or fifteen inch radius section. Thus, different configurations of horizontal track, i.e., with an integral ten, twelve or fifteen inch radius, for example, must be properly selected for a particular installation. Moreover, the length of the vertical track components may need to be adjusted to accommodate for lowered positioning of the horizontal track and integral radius.
Overhead doors are commonly counterbalanced with a spring assembly to assist in opening or raising of the door. Many commercial doors are very heavy, particularly insulated or wood doors, and a counterbalancing system utilizing one or more extension or torsion springs connected via cables and pulleys to the bottom section of the door is often used for this purpose. The springs and cables in such counterbalancing systems are maintained in tension and a significant amount of energy is stored in the spring to assist in lifting the door. Overtime, such springs may fail and the tension and energy stored in those springs is rapidly released which causes the overhead door system to malfunction. As such, professional installation, maintenance and periodic replacement of the counterbalancing system is often recommended.
Due to the size and weight of the overhead garage door components, and the general complexity associated with their assembly, overhead garage door systems typically are shipped by the manufacturer to a dealer for assembly at a site by a professional installer. It will be appreciated that the amount of parts which needs to be boxed and shipped by the manufacturer, as well as the length of time required for assembly of the overhead garage door system at each site, is affected by the number of components included in the overhead garage door system. Moreover, the dealer or installer must carry a greater inventory of parts as the number of unique track components in the overhead garage door system is increased.
Additionally, for garage door installations in low head room environments, various additional track components have typically been required. For example, one approach has been to provide dual parallel tracks, one above the other, with the upper track carrying the uppermost rollers of the overhead garage door. The upper track terminates close to the top of the garage door opening and thereby eliminates the need to guide the uppermost rollers below the level at which the curved portion of the track radius begins. Examples of this type of low head room track structure include U.S. Pat. Nos. 4,878,529; 4,119,133; 2,966,212; 2,436,006, and International Patent Application No. WO 96/36784.
Another approach to low head room installations has been to provide dual parallel tracks, arranged side-by-side, with one of the tracks carrying the uppermost rollers of the overhead garage door and the other track guiding the remaining rollers. Examples of this type of track system arrangement include U.S. Pat. Nos. 4,379,478; 2,064,470; and 2,045,060.
In yet another approach, as disclosed in Canadian Patent No. 657,377 and U.S. Pat. No. 1,990,870, for example, the requirement for parallel upper/lower or side-by-side tracks has been eliminated through the use of dual radius tracks mounted integrally on a corner bracket. The corner bracket includes a primary track radius that joins the horizontal and vertical track components, and an integral, auxiliary track radius that terminates near the top of the garage door opening. The auxiliary track radius guides uppermost rollers of the overhead garage door while the primary track radius guides movement of the remaining rollers between the vertical and horizontal tracks.
With this known approach, however, the primary and auxiliary track radiuses are not separable from the corner bracket, so the primary track radius cannot be used without the auxiliary track radius in normal head room installations. Moreover, in this known approach, use of the dual radius corner bracket requires the rollers extending from the side edges of the overhead garage door to be placed in a special staggered arrangement, or auxiliary rollers to be mounted to the side edges of the garage door.
One solution to many of these problems is disclosed in U.S. Pat. No. 6,047,761 (the “'761 patent”), assigned to the assignee of the present invention and hereby incorporated by reference in its entirety. The overhead door system disclosed in the '761 patent includes a pair of horizontal track members, a pair of vertical track members and a pair of primary track radius members interconnecting the horizontal and vertical track members on the opposite sides of a garage door opening. In the '761 patent, each of a pair of short radius track members extends from one of the primary track radius members to guide the uppermost rollers of an overhead sectional door. The short radius track members terminate close to the top of the door opening and thereby eliminate the need to guide the uppermost rollers below the level at which the curved portion of the track radius members begin. The universal overhead door system of the '761 patent is particularly beneficial for smaller door openings and low head room environments.
The track members in the '761 patent include so-called short radius members that are rigid and fixed for attachment to the flag bracket and the primary track radius members. The short radius track member has a generally C-shaped channel configuration in which upper and lower flanges are connected on opposite ends of a central web to capture the uppermost roller on the door. In some situations, an installer must modify or adjust the horizontal, vertical or primary track radius components to accommodate variations in the garage door opening, unlevel or non-symmetric surfaces or the like. Commonly, this requires cutting or changing the length of the vertical track member to accommodate proper installation of the short radius track. Such modifications are required and significantly labor intensive and counter productive to an efficient and quality overhead door installation process.
Accordingly, there is a need in the overhead garage door industry for an overhead door system that is modular and easily configurable to accommodate different door opening sizes, doors of different thicknesses, and in low head room environments that maximize the vertical clearance of the garage door opening and encourage pleasant and safe operation.